With rapid expansion of such as notebook computer, mobile phone and electric car markets, high energy-density secondary batteries have been desired. Approaches to providing a high energy density secondary battery include a method of using a large-capacity negative electrode material and a method of using a nonaqueous electrolytic solution excellent in stability.
Patent Literature 1 discloses use of an oxide of silicon or silicate as a negative electrode active material of a secondary battery. Patent Literature 2 discloses a secondary-battery negative electrode having a carbon material particle capable of absorbing and releasing lithium ions, a metal particle capable of alloying with lithium, and an active material layer containing an oxide particle capable of absorbing and releasing lithium ions. Patent Literature 3 discloses a secondary-battery negative electrode material formed by coating the surface of particles having a structure in which silicon fine crystals are dispersed in a silicon compound, with carbon.
Patent Literature 4 and Patent Literature 5 describe that if silicon is contained in a negative electrode active material, polyimide is used as a negative electrode binder. Patent Literature 6 describes that sulfurane is used as a solvent of an electrolytic solution.